Abstract

The benthic macroinvertebrate communities of the Aysén River Basin were studied (44°45' - 46°15'S; 71°00' - 73°00'W). The samples were obtained from 14 sites distributed in the different subbasins to cover the largest variability in the fluvial landscape. The samplings of macroinvertebrates were carried out using a Surber sampler. In each place physical-chemical parameters of the water column were quantified (pH, electric conductivity, dissolved solids, temperature and dissolved oxygen). Physical parameters of the river were also considered (order of the river, slope, width, depth, current velocity, riverside typology, riparian vegetation and substratum). A total of 59 taxa were identified, most of which corresponded to immature states of insects (83%). The most diverse groups of insects were Plecoptera (19 taxa), Ephemeroptera (14 taxa) and Trichoptera (10 taxa). The classification and ordination analyses of stations carried out with the abundance data, allowed to recognize five groups of stations statistically different (P <0,05). The multiple regression analysis, showed that the only environmental variable that accounts for the observed biological patterns, was the Froude number, explaining 45,1% the variance of the biological data (r2 adjusted 0,451, p <0,05).